1. Field of the Invention
This invention pertains generally to apparatus for rendering fat from animal material.
2. Description of the Prior Art
A conventional apparatus for the continuous rendering of fat from animal material utilizes a series of heated, vertically spaced and interconnected horizontal cylinders or tubes for the sequential flow therethrough of material to be rendered. One such apparatus is disclosed in U.S. Pat. No. 3,410,882 granted Nov. 12, 1968. However, no provision is shown therein for rendering under vacuum conditions. Inasmuch as substantial water vapor in the form of product steam is developed, the continuous removal thereof, aided by the vacuum, during the process is most desirable. Further, the vacuum prevents the oxidizing of the product fat because of the airfree environment. U.S. Pat. No. 3,782,902 granted Jan. 1, 1974, and assigned to assignee of subject application discloses an apparatus to accomplish this result. The standpipe arrangement disclosed in this patent preserves the vacuum condition in the apparatus.
While the above-noted apparatus shown in U.S. Pat. No. 3,782,902 has proved to be relatively efficient, nevertheless the output of the apparatus could be improved. Because of the size of each tube, which may be 24 inches O.D. and the need to provide for the mounting of the agitator shaft on the ends thereof, the inlet and discharge were made through the tube wall. Of necessity, this restricted the length of the steam jacket to a dimension short of the full length of the tube. Also the agitator member had to have a length short of the full length of the tube to avoid interference with the discharge and to allow provision for a gate or dam to control material flow through the tube. Further, venting of the product steam was also provided through the tube wall and preferably at the discharge end. As a consequence of the above construction, the capacity of each tube in rendering or cooking output and evaporation rate is unduly low.